1. Field of the Invention
The present invention relates to, for example, an active matrix type liquid crystal display apparatus.
2. Description of the Related Art
There is known, a liquid crystal display apparatus has been applied to various fields such as an office automation equipment, a clock, and a television in terms of features of light weight, thinness, and low power consumption. Specially, an active matrix type display apparatus in which a thin film transistor switches a pixel can realize an excellent response. Therefore, the active matrix type display apparatus has been utilized to a display monitor for a computer or a television which are demanded to display a number of image data.
Recently, specifically, a projection type display apparatus in which a liquid crystal panel of several cm square in a panel size and over 10 μm in a pixel pitch and an optical system for projection are combined has been produced. The above liquid crystal display apparatus is demanded to increase an aperture ratio and to raise contrast of an image in order to realize a high quality image display.
In the above liquid crystal display apparatus, by a direct-current drive, generally, impurity ions are distributed unevenly in a liquid crystal layer or in an alignment layer on an electrode substrate to thereby generate a polarization of liquid crystal molecules. As a result, a voltage-transmittance characteristic changes, namely, a so-called “sticking phenomenon” occurs. To prevent the above, potential of the liquid crystal is typically refreshed by an alternate-current drive. Further, in the liquid crystal display apparatus, by driving the entire field at the same-potential, a minute fluctuation of transmittance due to a polarity reversal is easily observed as a flicker. Therefore, a line-reversal drive in which a polarity is reversed in each line or each several lines to chancel the flicker has been adopted.
By the above line-reversal drive, a potential difference is generated between adjoining pixel electrodes having different polarities, and the potential difference is almost double of that between a counter electrode and a pixel electrode. Therefore, a strong lateral electric strength is generated between the adjoining pixel electrodes in a vertical direction. The lateral electric strength causes a reverse tilt domain in which the liquid crystal molecules are arranged in a direction different from its original arrangement in a scan line direction.
Therefore, in the above line-reversal drive type liquid crystal display apparatus, in the case where a size of the pixel is approximately over 10 μm, a light leakage surrounding the pixel makes contrast to decrease. This is because that, by increasing an aperture ratio in order to improve a light utilization efficiency, a shield region is made small to thereby enable an observation of portions disturbed with the liquid crystal.
Accordingly, Japanese Unexamined Patent Publication (Kokai) No. 2004-118048 discloses that, in the line-reversal drive type liquid crystal display apparatus, a rubbing direction is selected so as to difficultly generate the reverse tilt domain to thereby prevent the light leakage generated in the vicinity of the scan line.